In my experience simple means limited when it comes to video.
To this end I am suggesting AVIsynth. Yes it is entirely script based and yes the scripts are in essence a programming language but the basic stuff is fairly trivial and adding in advanced stuff is also not too difficult.

You say blurring/box over a face, the easiest is naturally for a static face with moving being harder (even on TV with the expensive engineers and equipment you will see it wobbly or far bigger than necessary).
Owing to the nature of the application it is simple to tweak things (or even run 10 tests side by side).
Layer is the command you want for avisynth (there was a thread a few months back where I did just that for someone as well):http://avisynth.org/oldwiki/index.php?page=Layer

Failing that think duality of knowledge/duality of technology. I am sure you have seen attempts to remove logos at some point (the well done ones are fantastic but few do them that well). Blurred just about begins to cover that....
Fairly ancient (the forum at doom9 has some fantastic stuff) but:http://www.doom9.org/index.html?/capture/delogo.html